Bag top closure



Jul 121, 1964 Filed Sept. 6, 1960 R. H. AYRES ETAL BAG TOP CLOSURE 2 Sheets-Sheet 1 INVENTORJ RICHARD H. HYREs BY HARoLD K. Fox

Arron/vera- July 21, 1964 R. H. AYRES ETAL 3,141,601

BAG TOP CLOSURE Filed Sept. 6, 1960 2 Sheets-Sheet 2 IN VEN TORJ fi/C/MRD l7. flYREs y HAROLD K Fox 147- TQRNE YJ',

United States Patent O 3,141,601 RAG 'IUP CLGSURE Richard H. Ayres and Harold K. Fox, Minneapolis, Minn, assignors to Bemis Bro. Bag Qompany, Minneapolis, Minn, a corporation of Missouri Filed Sept. 6, 1960, Ser. No. 54,090 8 Claims. (Cl. 22Q-62) This invention relates to new and useful improvements in bag top closures of the general type wherein the walls of the bag top are pressed into flatwise relation and secured together by suitable means such as sewing, bonding and the like, to provide a leakproof closure.

Such bag tops may also have a sealing tape folded over the flattened bag top walls and secured thereto to reinforce and strengthen the composite closure. While such bag top closures have proven quite satisfactory in actual use, there always exists the possibility that the bonded together walls of the bag top may separate sufficiently to cause a small leak to develop in the closure, because of the manner in which the bag top walls are secured together, and especially if the bag top closure embodies a row of stitching.

An important object of the present invention therefore is to provide an improved bag top closure which readily lends itself for use in the operation of closing and sealing the open tops of flexible walled bags, both large and small, and regardless of whether the bag bodies are constructed of paper, polyethylene or other types of plastic materials, with the assurance that when the bag tops are so closed and sealed, they are not likely to become leaky if the filled bag bodies are roughly handled in transit, or otherwise.

A further object of the invention is to provide a bag top closure for large flexible walled bags comprising a plurality of independent seals, preferably three, extending the length of the bag top which cooperate to hermetically seal the closed bag tops against leakage, and whereby should one of said seals develop a leak, the remaining seals will protect the contents of the bag body against damage which might result from a leaky seal.

A further and more specific object of the invention is to provide a bag top closure comprising a multiplicity of seals extending the length of the bag top, and certain of said seals being spaced apart vertically to provide upper and lower horizontal seals, and a thin flexible thermoplastic coated sealing tape being applied over the flattened bag top walls and having its opposed walls extending downwardly into engagement with the side surfaces of the bag top walls, the lower marginal edge portions of the tape walls extending below the lower edge of the lower horizontal seal, whereby said downwardly extending marginal edge portions are not directly engaged by the heating means, when the heating means are subsequently actuated to press the tape walls into bonding engagement with the bag top walls to hermetically seal the bag top against leakage; and the unattached overhanging lower marginal edge portions of the tape walls preventing the heating elements from directly contacting the bag top walls below the lower edges of the tape which, in some instances, may develop weakened areas in the bag walls, particularly if the bag bodies are constructed of a material which may be allergic to high temperatures, such as some plastics, whereby weakened areas might develop in the bag walls adjacent to the lower edges of the sealing tape which could give way under tension, particularly in larger bags.

A further object of the invention is to extend the side walls of the sealing tape downwardly beyond the lower edge of the lower transverse seal whereby said marginal edge portions will not be engaged by the heat applying means, whereby the thermo-plastic film on said marginal lidilfil Patented July 21, 1964 .walls to serve as protective skirts to prevent tearing of the bag top walls adjacent to the closure, as a result of tensional strains or pressures to which the bag walls may be subjected.

Other objects of the invention reside in the provision of a bag top closure of the character disclosed which is suitable for both flat tube bags and gusseted type bag bodies; and in the provision of such a closure which is extremely simple and inexpensive in construction, and is so designed that it may readily be accomplished on bag top closing machines now in general use in the trade.

These and other objects of the invention and the means for their attainment will be more apparent from the following description taken in connection with the accompanying drawings.

In the accompanying drawings here has been disclosed a method designed to carry out the various objects of the invention, but it is to be understood that the invention is not confined to the exact features shown, as various changes may be made within the scope of the claims which follow.

In the drawings:

FIGURE 1 is a perspective view showing the formation of a bag top closure in accordance with the invention;

FIGURE 2 is an enlarged sectional elevation on line 2-2 of FIGURE 1, showing the vertically spaced sealing areas;

FIGURE 3 is a top plan view showing a plurality of flattened bag tops passing successively through a heat sealing means;

FIGURE 4 is a view, partially in section, showing the upper portion of a flat tube bag having its top Wall portions closed and sealed in accordance with the present invention, and also showing the vertical spacing between the horizontal sealing areas extending the length of the bag top;

FIGURE 5 is an enlarged cross-sectional elevation on the line 5-5 of FIGURE 4, showing the protective skirts formed by the lower unattached marginal edge portions of the tape walls, partially outwardly flexed;

FIGURE 6 is a view similar to FIGURE 4, but showing the invention applied to the top end of a single ply flat tube bag body constructed of polyethylene or other plastic material;

FIGURE 7 is an enlarged cross-sectional elevation on the line 77 of FIGURE 6; and

FIGURE 8 is a view similar to FIGURE 7, showing the protective skirts formed by the lower unattached marginal edge portions of the tape walls outwardly flexed by expansion of the bag walls adjacent thereto.

In FIGURES 1, 2 and 3 of the drawings the invention is shown embodied in a gusset type bag comprising a body, generally designated by the numeral 2, comprising inner and outer paper plies 3 and 4, and an inner moisture proof liner 5, preferably of polyethylene, or other material adequate for the purpose, as best shown in FIGURE 2. In such bags it has been customary in the past to press the bag top walls into flatwise relation and secure them together by stitching. In some instances a strip of sealing tape has been folded over the sewn bag tops to prevent leakage through needle holes.

An important feature of the present invention is to provide an improved bag top closure comprising a plurality of vertically spaced horizontal sealing areas or Zones, preferably three in number, here shown designated by the numerals 6, 7 and 8. Seal 8 is formed by a thin flexible strip of thermoplastic coated sealing tape 9, folded over the flattened bag top Walls in the operation of closing and sealing the bag top. Sealing areas 6 and 7 are spaced apart vertically by non-sealing areas 10 formed as a result of the heating means utilized for sealing the bag top walls not directly engaging the walls of the sealing tape in the non-sealing areas 10, as will be understood by reference to FIGURE 2. By providing two or more vertically spaced horizontal seals, as herein disclosed, a leakproof closure is assured, and at the same time the resultant bag top closure is rendered more flexible, and hence is less likely to fracture as a result of rough handling in transit.

In the formation of the novel bag top closure herein disclosed, the bag top walls are initially pressed into fiatwise relation by suitable means such as disclosed, for example, in the co-pending application of Frank L. Hopkins and Richard H. Ayres, for Bag Top Closing and Sealing Machines, Serial No. 13,376, filed March 2, 1960, now Patent No. 2,978,852. Simultaneously, the strip of thin, flexible thermo-plastic coated sealing tape 9 is folded over the top edges of the bag top walls and is securely bonded or fused thereto by the application of heat and pressure, as will be understood by reference to FIGURES l, 2 and 3. If the bag is a gusseted or intuck type, as shown in FIGURE 1, the end walls are intucked between the side walls of the bag top before the bag top walls are pressed into flatwise relation preparatory to applying the sealing tape thereto, as is well known in the art.

To afford a clearer understanding of the formation of the composite bag top closure, there is schematically illustrated in FIGURES 1 and 3, a heat and pressure applying mechanism, generally designated by the reference character B. This mechanism is shown and described in detail in the above noted pending application, and forms no part of the present invention. Mechanism B, as here shown, comprises two pairs of dual belt runs 11 and 12 which dual pairs of belt runs are laterally spaced apart to provide therebetween a travel path for the bag tops. Belt runs 11 and 12 of each pair of belt runs are vertically spaced apart and are directly engaged by a plurality of similarly spaced heating elements 1.3 and 14, under spring pressure. The heat from said heating elements is transmitted through their respective belt runs to the tape and bag top walls, which reactivates the thermoplastic coating on the tape walls, and if the bag top has a polyethylene or plastic liner 5 therein, as shown in FIG- URE 2, said liner also becomes reactivated, whereby all of the bag top walls are intimately fused together along the vertically spaced sealing areas or zones 6 and 7.

Another important feature of the invention is to provide a leakproof bag top closure which embodies no stitching, and hence has no needle holes through which leakage may subsequently occur. To accomplish this the bag top and tape walls are bonded or fused together along the vertically spaced independent sealing areas or zones 6 and 7, as hereinbefore stated, and as clearly shown in FIGURES 2, 4, 5 and 6. This seals extend the full length of the flattened bag tops.

Another feature of the present invention resides in the unique design of the heat seal pattern which, as clearly illustrated in FIGURES 4 and 6, comprises the two elongated sealing areas or zones 6 and 7, spaced apart vertically by the non-sealing areas 10, resulting from the vertical spacing between the heating elements 11 and 12 of mechanism B.

In the operation of closing and sealing a plurality of bag tops, the bag tops with the sealing tape folded thereover, are successively delivered into the heat and pressure applying mechanism B, indicated in FIGURE 3. As the bag tops pass therethrough, the vertically spaced heating bands 11 and 12 engage the walls of the thin thermoplastic coated tape and compress the flattened bag top walls therebetween. Such action reactivates the thermoplastic coating on the tape walls, and thereby fuses the tape and bag top walls together along the vertically spaced sealing areas or zones 6 and 7, as hereinbefore stated. See FIGURES 1, 4 and 6. By vertically spacing apart the horizontal sealing areas 6 and 7 and simultaneously folding the sealing tape 9 over the bag top, as above described, an effective triple seal is provided, as will be understood, whereby there is little or no danger of a leak occurring.

Another important feature of the invention resides in the means provided at each side of the sealed bag top for preventing fracturing of the bag top walls adjacent to the bag top closure, when the bag tops are subjected to severe strains or tension. It is known that some materials such as polyethylene, and various other plastic materials, may be weakened if subjected to the direct application of heat thereto. To prevent the heating means from directly contacting the walls of the bag body, the lower marginal edges of the sealing tape are extended downwardly well below the lower edges of the heat applying means 11 and 12 which produce the lower horizontal sealing areas 6, as clearly shown in the drawings, whereby the lower marginal edge portions of the sealing tape 9 are not directly engaged by the heating elements, and hence do not become bonded to the bag top walls. They thus remain free and unattached and serve to provide flexible protective skirts 15 for preventing damage to the bag top walls adjacent to the closure.

FIGURES 4 and 5 show the invention embodied in a flat tube bag comprising an outer paper ply 16 having a plastic liner or moisture barrier 17 therein. The same procedure is followed in closing and sealing the open tops of such bags.

FIGURES 6, 7 and 8 disclose a bag in which the walls of the bag body 18 are constructed from a relatively heavy polyethylene or other plastic material, in which the bag top walls are pressed into flatwise relation with one another and directly bonded together and with the walls of the sealing tape, when the walls of the sealing tape are pressed thereagainst by the application of heat and pressure, in a manner similar to the forms shown in FIGURES 1 through 5, inclusive.

Another important feature of the invention resides in extending the end portions 19 of the sealing tape beyond the ends of the bag top as clearly illustrated in FIGURES 4 and 5. By so extending the ends of the sealing tape, the opposed walls of the tape at the ends of the bag top become intimately fused together, as the bag tops pass between the heating means, whereby should a leak develop in the lower seal 6, and establish communication between the interior of the bag body and the non-sealing area or zone it), the upper seal 7 and the sealed tape ends 19 will provide complete protection and block leakage to the atmosphere.

By providing two or more transverse vertically spaced sealing areas or zones 6, 7 and 8, as herein disclosed, provides a very desirable leakproof safety factor in bag top closures of this general type. The thin flexible thermoplastic coated sealing tape conforms readily to any irregularities in the bag top walls, and because of the extreme pliability of the sealing tape walls, the resultant bag top closure may be folded or otherwise distorted when in use without danger of damaging the sealed bag top.

The closure, as herein disclosed, comprises three separate seals, which has been found adequate to produce a hermetically sealed bag top capable of adequately resisting rough handling to which such filled bags are frequently subjected, when transported from one place to another. It is to be understood, however, that the number of seals embodied in the composite bag top closure may be varied, as desired, without departing from the scope of the invention.

It is apparent that many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof. The specific embodiments described are given by way of example only and the invention is limited only by the terms of the appended claims.

We claim as our invention:

1. A closed flexible walled bag enclosing material contained therein,

(A) the top walls of said bag being (1) pressed together (2) in flatwise relation,

(3) the inside surfaces of said top walls of said bag being thermosensitive,

(B) said flattened bag top walls being (1) adhesively secured together (2) along at least one relatively wide fusion bonding area (a) adjacent the top edge of the bag and (11) extending the width of the bag, and (C) a strip of thin flexible thermoplastic tape (1) extending over and (2) further sealing the flattened top end of said (D) said bag top and tape being (1) adhesively secured together (2) along a relatively wide fusion bonding area (a) coextensive with and (b) overlying the bonding area adhesively securing the top walls together.

2. A bag according to claim 1 further characterized in that the lowermost marginal edge portions of said tape are free and unbonded to the bag walls for a distance extending well below the lowermost edge of the fusion bonding area.

3. A bag according to claim 1 further characterized in that said bag is composed of multi-ply paper walls and a moisture proof thermosensitive plastic liner coextensive therewith, and said tape is composed of paper having a thermosensitive adhesive coating thereon.

4. A closed flexible walled bag enclosing material contained therein, the top walls of said bag being pressed together in flatwise relation, the inside surfaces of said top walls of said bag being thermosensitive, said flattened bag top walls being adhesively secured together along a plurality of relatively wide fusion bonding areas adjacent the top edge of the bag and extending the width of the bag, and a strip of thin flexible thermosensitive tape extending over and further sealing the flattened top end of said bag, said bag top and tape being adhesively secured together by a plurality of relatively wide parallel vertically spaced independent fusion bonding areas each extending the width of the bag body and coextensive with and overlying the bonding areas adhesively securing the bag top walls together.

5. A closed flexible walled bag enclosing material contained therein, the top walls of said bag being pressed together in flatwise relation, the inside surfaces of said top walls of said bags being thermosensitive, said flattened bag top walls being adhesively secured together along a plurality of fusion bonding areas adjacent the top edge of the bag and extending the width of the bag, and a strip of thin flexible thermosensitive tape extending over and further sealing the flattened top end of said bag, said bag top and tape being adhesively secured together by a plurality of relatively wide parallel vertically spaced independent fusion bonding areas each extending the width 6 of the bag body and coextensive with the bonding areas adhesively securing the bag top walls together, the lowermost marginal edge portions of said tape being free and unbonded to the bag walls for a distance extending well below the lowermost edge of the fusion bonding areas.

6. A closed flexible walled bag enclosing material contained therein, the top walls of said bag being pressed together in flatwise relation, said bag being composed of multi-ply paper walls and a moisture proof thermosensitive plastic linear coextensive therewith, said flattened bag top walls being adhesively secured together along a plurality of relatively wide fusion bonding areas adjacent the top edge of the bag and extending the width of the bag, and a strip of thin flexible paper tape having a thermosensitive adhesive coating thereon extending over and further sealing the flattened top end of said bag, said bag top and tape being adhesively secured together by a plurality of relatively wide parallel vertically spaced independent fusion bonding areas each extending the width of the bag body and coextensive with and overlying the bonding areas adhesively securing the bag top walls together.

7. A closed flexible walled bag according to claim 6 further characterized in that the lowermost marginal edge portions of said paper tape are free and unbonded to the bag walls for a distance extending well below the lowermost edge of the fusion bonding areas.

8. A closed flexible walled bag enclosing material contained therein, the top walls of said bag being pressed together in flatwise relation, said bag being composed of multi-ply paper walls and a moisture proof thermo-sensitive plastic liner coextensive therewith, said flattened bag top walls being adhesively secured together along at least one relatively wide fusion bonding area adjacent the top edge of the bag and extending the width of the bag, and a strip of thin flexible paper tape having a thermosensitive adhesive coating thereon extending over and further sealing the flattened top end of said bag, said bag top and tape being adhesively secured together by at least one relatively wide fusion bonding area extending the width of the bag body and coextensive with and overlying the bonding area adhesively securing the bag top walls together, the lowermost marginal edge portions of said tape being free and unbonded to the bag walls for a distance extending well below the lowermost edge of the fusion bonding area.

References Cited in the file of this patent UNITED STATES PATENTS 1,603,207 Huston Oct. 12, 1926 2,345,434 Sterling Mar. 28, 1944 2,403,756 Read July 9, 1946 2,524,030 Allen Oct. 3, 1950 2,622,986 Snyder et al Dec. 23, 1952 2,672,268 Bower Mar. 16, 1954 2,751,140 Brady June 19, 1956 2,868,435 Fischer Jan. 13, 1959 2,899,347 Kindseth Aug. 11, 1959 2,975,955 McCurry Mar. 21, 1961 3,009,627 Ottinger Nov. 21, 1961 3,014,638 Farley Dec. 26, 1961 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N00 3 l4l 60l July 21 1964 Richard Ho Ayres et ala It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2 line 18 for "here" read there column 3 line 54 for "This" read These column 6 line 10 for "linear" read liner Signed and sealed this 24th day of November 1964c,

(SEAL) Attest:

ERNEST W. SWIDER Commissioner of Patents 

4. A CLOSED FLEXIBLE WALLED BAG ENCLOSING MATERIAL CONTAINED THEREIN, THE TOP WALLS OF SAID BAG BEING PRESSED TOGETHER IN FLATWISE RELATION, THE INSIDE SURFACES OF SAID TOP WALLS OF SAID BAG BEING THERMOSENSITIVE, SAID FLATTENED BAG TOP WALLS BEING ADHESIVELY SECURED TOGETHER ALONG A PLURALITY OF RELATIVELY WIDE FUSION BONDING AREAS ADJACENT THE TOP EDGE OF THE BAG AND EXTENDING THE WIDTH OF THE BAG, AND A STRIP OF THIN FLEXIBLE THERMOSENSITIVE TAPE EXTENDING OVER AND FURTHER SEALING THE FLATTENED TOP END OF SAID BAG, SAID BAG TOP AND TAPE BEING ADHESIVELY SECURED TOGETHER BY A PLURALITY OF RELATIVELY WIDE PARALLEL VERTICALLY 